Regulator for electrically heated hot plates



Sept. 7, 1954 M. WALTHERT 2,683,683

REGULATOR FOR ELECTRICALLY HEATED HOT PLATES Filed Nov. 5, 1951 Patented Sept. 7, 1954 REGULATOR FOR ELECTRICALLY HEATED HOT PLATES Max Walthert, .Lucerne, Switzerland, assignor to 'Landis & Gyr, A. G., a body corporate of Switzerland Application November 5, 1951, Serial No. 254,942

Claims priority, application Switzerland November 4, 1950 Claims. 1

This invention is directed to a novel cooking plate regulator.

Objects and advantages of the invention will. be set forth in part hereinafter and in part will be obvious herefrom, or may be learned by practice with the invention, the same being realized and attained by means of the instrumentalities and combinations pointed out in the appended claims.

The invention consists in the novel parts, constructions, arrangements, combinations and improvements herein shown and described.

An object of this invention is to provide a novel cooking plate regulator whereby different stages of heating may be obtained by fixing in different positions a manually operable regulating knob.

A further object of my invention is to provide a novel cooking plate regulator whereby a continuous regulation of heating power is obtained by a unique combination of elements including a number of cooperating switches.

The accompanying drawings, referred to herein and constituting a part hereof, illustrate an embodiment of the invention, and together with the description, serve to explain the principles of the invention.

Figure 1 is a perspective view of an embodi ment of my invention.

Figure 2 is a top View showing a circular disc having its upper portion bent to form a cam to effect longitudinal displacement of the operatin shaft for the invention.

The invention in general is directed to a cooking plate regulator comprising two filament resistances connected in parallel, a hand actuated switch connected in the circuit of the first filament resistance, said switch being dependent on a regulating knob, and a tumbler switch connected in the circuit of the said filament resistance, said tumbler switch being controlled by a bimetal construction, said bimetal constructlon being opposite said tumbler switch and be ing heated by at least one secondary short circuit winding of a heating transformer, the pri mary winding of which is connected in parallel with the second filament resistance.

The tumbler switch in the above construction is operatively connected to the regulating knob. A stationary index cooperates with the regulating knob, which has a two position scale so that when the knob is in one position with respect to the stationary index, both of the filament resistances become effective, this stage being the parboiling stage; while when the regulating knob is turned to a second position, the first filament resistance is disconnected and the second filament resistance is switched on and off.

In order to describe the invention more specifically, I now refer to Figure 1. Two conductors a and b of a high voltage line have been connected thereto, by means of a switch I, two heating filament resistances 2 and 3, said resistances being connected in parallel for heating an electric boiling plate 4. A switch 5 is positioned in the circuit of the filament resistance 2, while a' tumbler switch 6 is positioned in the circuit of the filament resistance 3, said tumbler switch being designed so that it is normally closed and open only during actuation.

The two switches I and 5 are actuated by cam discs I and 8 which are rigidly connected to a rotatable shaft I0 which is regulated by regulating knob 9. The regulating knob 9 is provided with a scale I I, the position of which may be read from a stationary index I2 arranged opposite it. A notched disc I4 cooperates with spring I3, said disc It being rigidly connected to the shaft ID to permit one to establish the position of 9 and M of the scale I l.

The cam disc I is so designed that when shaft I0 is turned out of position the switch I is closed but switch 5 is open. When the shaft is turned to position M, the cam 8 is so designed that switch 5 is closed which means that both switches I and 5 are closed and the filament resistances 2 and 3 heat the plate 4 to a parboiling stage.

A lifting cam I5 shown in plan View in Figure 2 is rigidly connected to the shaft I0 and is guided between two pins I6 connected to a part of regulator housing (not shown). The lifting cam as shown clearly in Figure 2 has corrugated edges so that when the shaft I0 is rotated clockwise from position 0 to position M by means of the knob 9, it engages an edge of the cam I5 and is moved longitudinally from right to left. Likewise, when the shaft is rotated counterclockwise from position M to 0, it is moved longitudinally from left to right. The right hand end of the shaft I is rotatable in the housing of the tumbler switch 6 but cannot be displaced, which means that the tumbler switch 6 takes part in the longitudinal displacement of the shaft it), said tumbler switch being guided by means of a parallel guide spring 11, said guide spring ll being rigidly connected at the points It to the regulator housing (not shown). Even though the shaft l0 and tumbler switch 6 have been displaced to the right, the switches l and are constructed so that they are still closed.

An actuating knob 19 of the tumbler switch 5 is positioned on the right hand side of it and is directly opposite an actuating pin 2! rigidly connected to the free end of a compensation bimetal wing 26. The compensation bimetal wing 20 is connected to two active bimetal arms 22 with the entire bimetal construction being fixed to a sheet stack 23 of a transformer, the primary winding M of which is connected in parallel to the filament resistance 3. Two short-circuit windings 25 are arranged as secondary windings and rigidly connected to the bimetal arms 22. When a current is passed through the primary winding 24, a short-circuit current is produced in each of the two short-circuit windings which heats the bimetal arms.

The two short-circuit windings 25 may be made in one part and connected to the wing 20, so that the wing 20 forms the active part of the bimetal construction, while the two bimetal arms 22 serve for compensation. Also, the displacement of the tumbler switch may be effected by the lifting cam l5 acting directly on the tumbler switch while the shaft Hi no longer executes a longitudinal displacement.

My invention operates as follows. In the, zero position the shaft It is in its right hand terminal position and the switches l, 5 and 6 are all open, said tumbler switch 6 being open by means of the actuating pin 2! pressing the actuating knob I9 of the tumbler switch. When the regulating knob is turned into position M, the shaft Iii moves into its left hand terminal position and the two switches l and 5 and the tumbler switch 6 close. A corresponding part current now fiows across each of the two filament resistances 2 and 3 and the primary winding 2d of the heating transformer receives power line voltage. The shortcircuit windings 25 become heated and the bimetal arrangement is deformed.

At this point, the actuating pin 2| cannot actuate the tumbler switch 6 so that the boiling plate is heated at a maximum for a period called parboiling time. When the material being heated has been cooked sufiiciently, the regulating knob 9 is turned in counterclockwise direction so that the shaft it by means of the lifting cam i5 is displaced .to the right, which causes the actuating knob 59 to get into the effective range of the actuating pin 2! of the bimetal construction. At this point switch i is closed but switch 5 is open.

, Current no longer fiows through the filament resistance 2 While an impulse type current now flows through the filament resistance 3, the impulse duration depending on the distance set by means of the regulating knob 9 between the actuating knob l9 and the actuating pin 2!, the intermittent or pulsating current being controlled by the opening and closing of the switch '5 under the influence of the bimetal member 20. The nearer the tumbler switch 6 is pressed to the bimetal arrangement, the longer will be its period of opening and the smaller will be the output fed to the boiling plate. If the regulating knob 9 is finally turned to the position 0 the tumbler switch 6 remains continuously open and simultaneously the switch l is also opened, which causes the boiling plate to be disconnected at all poles from the line a, b. The adjusted metering of energy remains constant even in the case of fluctuations of the line voltage, as the amount of energy supplied to the boiling plate is proportional to that needed by the bimetal in its adjusted connections.

The invention in its broader aspects is not limited to the specific mechanisms described but departures may be made therefrom within the scope of the accompanying claims without departing from the principles of the invention and without sacrificing its chief advantages.

I claim:

1. A cooking plate regulator adapted to provide continuous regulating of heating power by supplying electric energy by impulses comprising first and second filament resistances connected in parallel to each other, a normally rotatable shaft axially movable to different extents by rotation of the shaft, a first switch actuated by rotation of the shaft to supply power to one resistor, a second switch carried and moved by the axial movement of the shaft and opened and closed by movement in line with the shaft, a bimetal element movable toward and from the second switch to open and close the second switch, the amount of movement of the bimetal element needed to close the second position being determined by the axial position of the shaft, said bimetal element being heated by a secondary short-circuit winding of a heating transformer, the primary winding of said transformer being connected in parallel with the second filament resistance whereby said regulating knob may be turned to two operable positions, the first position being where both filament resistances are effective and the other operable position being where saicl first filament resistance is disconnected and said second filament resistance is continuously switched on and off.

2. A cooking plate regulator as defined in claim 1 in which the regulating knob is rigidly fixed to an operating shaft and said first switch is controlled by means of a cam fixed to said operating shaft whereby said first filament resistance is closed only when said regulating knob is in said first mentioned position.

3. A cooking plate regulator as defined in claim 2 in which a lifting cam is attached to said opering first and second filament resistances con-- nected in parallel to each other, an axially movable shaft moved axially by rotation thereof, a switch actuated by rotation of the shaft for controlling power supplied to one of the resistances, a second switch axially moved with the shaft, a bimetal element moving axially of the shaft for actuating the second switch, said bimetal element including a wing which is operatively connected to the second switch and is deformed by being heated by a secondary short-circuit winding of a heating transformer, the primary winding of said transformer being connected in parallel with the second filament resistance whereby said regulating knob may be turned to two operable positions, the first position being where both filament resistances are effective and the other operable position being Where said first filament resistance is disconnected and said second filament resistance is continuously switched on and off.

5. A cooking plate regulator as defined in claim 4 in which the bimetal construction contains one short-circuit Winding.

6 References Cited in the file of this patent UNITED STATES PATENTS Number 5 2,068,425 2,140,362 2,182,048 2,438,345 2,451,225 10 2,576,336

Name Date McCabe Jan. 19, 1937 Kintzing Dec. 13, 1938 Elmer Dec. 5, 1939 Miller Mar. 23, 1948 Johnson Oct. 12, 1948 Hilsinger Nov. 27, 1951 

